(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

[tex] int^{infty}_{0} \frac{x^3sinx}{(x^2+1)(x^2+9)} dx [/tex]

2. Relevant equations

I understand the value of the integral will be 2 * pi * [sum of residues]

and I am also aware of the formula

Res_{z=z_0} f(z) = [tex] \frac{g^{m-1} (z_0)}{(m-1)!} [/tex]

3. The attempt at a solution

I know the poles exsit and are x= + / - i and x = +/- 3i

only 2 in the countour and that is x=i and x=3i

so I get stuck here because all the examples have a bit of working out with a less than or equal to sign and an absolule value, which shows as it goes to zero R goes to inifity... I just don't understand how to set that bit up and why it is necessary, if you know what i'm talking about, can you please explain it to me?

Thanks

Laura

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# Homework Help: Is this the right working out for integral x^3sin(x)dx/[(x^2+1)(x^2+9)]

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